Materials for electronic circuit encapsulants, heat sinks, and sealants and the like for the microelectronics industry are generally mixtures of solidified polymeric materials, ceramic fillers, and other minor ingredients. The purpose for such encapsulants or heat sinks is to provide effective heat removal from electronic integrated circuits as well as to protect the electronic circuits from moisture, mobile ion contaminants, and ultraviolet, visible, and alpha-particle radiation. Critical properties of encapsulating and heat sink materials include high strength, high thermal conductivity, low coefficients of thermal expansion, moisture resistance, good thermal shock resistance, flexibility, and good electrical properties, such as being highly electrically insulative.
Several types of polymeric materials for use in microelectronic encapsulation and the like have been taught in the past. However, dramatic size-reduction trends and faster circuits in the microelectronics industry have resulted in smaller devices and packages which unavoidably generate more heat per unit area of the device or package. Consequently, there is a great interest in improved compositions with properties to better meet the current and future needs of the microelectronics industry.
It is, therefore, a primary object of the present invention to provide thermally-conductive composites for microelectronic applications which have high strength, high thermal conductivity, low coefficients of thermal expansion, high moisture resistance, good thermal shock resistance, greater flexibility, and good electrical properties, such as electrical insulative properties, are easily manufactured, and may be used at elevated temperatures. It is another object of the present invention to provide methods for making such composites.